Great list I like how you are constantly updating the info Perry Reeves looked so young. Michael O'Neill (Transformers, Prison Break) was in 1998 episode he played The Patrol Captain in Drive. I could have sworn he was also in Squeeze as the FBI agents taking over the stakeout from Mulder. Also shouldnt the number of episodes be shifted down a number or you do not consider the pilot as episode 1?

Also Mark Sheppard who was the lawyer on Battlestar Gallactica (2004), Chuck The Ring Leader, Firefly as Badger and Sliders. I am watching the Series from the Beginning for the first time and I have OCD for people I recognize I will keep you updated.

The Ice episode from season one has alot of good guest stars the most I have ever seen in one episode of a show. Jeff Kober (Buffy, Sons of Anarchy), Xander Berkeley (24, Nikita(2010)), Steve Hytner (Banya on Seinfeld and Hung). I noticed you have this Deadwood theme the actor on your list Pruitt Taylor Vince was also on Deadwood which is an amazing show I just watched again.

Jesse L Martin of Law And Order and Smash in s6 episode 19 The Unnatural.
Darren McGavin the father in A Christmas Story as old Arthur Dales in s5 episode 15 Travelers and Agua Mala
Silas Weir Mitchell who plays Monroe on Grimm in s6 episode 16 Agua Mala as looter.